Patterning MXene RFID Antennas via Surface Hydrophobicity Modulation

MXenes are an emerging class of 2D transition metal carbides and nitrides, known for their mechanical, chemical, and electrical properties, which make them suitable for electromagnetic applications such as antennas and radio frequency identification (RFID) devices. This research demonstrates that MXene-based RFID antennas can be patterned by modifying the hydrophobicity of a hydrophilic paper substrate. A Ti₃C₂T_x MXene colloid with a concentration of 32 mg g^-1 with a conductivity of (≈10 000 S cm^-1) is used to fabricate conductive traces of RFID antennas through dip-coating, using a superhydrophobic layer patterning technique. Ink spreading is minimized by controlling the water repellency of the surfaces and taking advantage of the inherent hydrophilicity of MXene, resulting in improved pattern fidelity. The versatility of the proposed patterning method is demonstrated through the fabrication of three different RFID antenna tags, including dipole, meander, and T-matched antennas, designed to operate at ultrahigh frequency (UHF) (800-920 MHz). The method also enabled impedance matching for dipole and meander-shaped RFIDs to 50 Ω, achieving ≈ 97% efficiency compared to copper-based counterparts fabricated using subtractive methods. This approach enables well-defined, self-confined deposition and offers a scalable process for MXene conductive traces and microstrip lines patterning.